The ratings success of
"The Big Bang Theory" is paying off in a big way for CBS. How big? More than $300,000 per 30-second commercial big.

The average ad on the show costs $326,260, according to a survey of media buyers
by Adweek. Outside of NFL telecasts -- which comman more than half a million dollars per 30 seconds -- it's the most expensive show for advertisers on TV.

Not without reason: "Big Bang" had its highest-rated season ever in 2012-13, and its first few episodes this season are running ahead of that average. Its first two episodes of the fall averaged 18.6 million viewers and a 5.4 rating among adults 18-49 in overnight ratings, putting it in the Top 3 on broadcast TV in both measures.

Among the other shows drawing big bucks from ad sales are
"The Voice" ($264,575 for its Monday show),
"Modern Family" ($257,435) and
"The Simpsons" ($256,963). The first two are strong ratings performers across the board, and while "The Simpsons" is lower in the overall rankings, it draws a heavy concentration of younger male viewers, for which advertisers are willing to pay a premium.

The most expensive new series of the fall is
"The Blacklist," which commands just under $200,000 per 30-second ad. It's proving to be a decent buy so far, as its early episodes have drawn solid ratings.